Category Archives: 4K Ultra HD TV

I’ve been asked to explain how it is possible that by moving our entire infrastructure to 10 bit color could possibly deliver both better quality images and give us more efficient (ie smaller) streams. We have been overhauling our delivery of 4K streams in an upcoming release of our engine and have moved the entire process to 10 bit. This not only allows us to provide a real time delivery of HDR10 streams, but also for SDR displays gives us better quality with smaller streams, saving delivery costs.

Initially when you think about adding more bits per pixel it makes sense that you get better image quality, but getting better efficiency doesn’t seem to make sense, and I’ve been asked “how is this possible”. By moving the entire workflow to 10 bit, we are able to compress with less errors. To deliver the best quality video possible, you want to have as few “errors” in the encoded version when comparing it to the original uncompressed version. The process by which an encoder reduces the file size is called quantization . Comparing the original image to the resultant image in compression there can be a difference of pixels , however that difference is unaffected by the depth of those pixels.

During the encoding process, a 10 bit image has roughly 20% more data to be compressed. During the hardest parts of encoding where there is high speed movement or large blocks of the screen ar changed, the higher bit rate allows for higher accuracy in recreating the original image thereby giving a better quality result. Since we have to encode at the same target bit rates, whether 8 bit or 10 bit, you end up with a better image at the same bit rates. This is mostly due to the underlying math that generates less errors in 10 bit than in 8 bit.

Given that our mastering process starts with an uncompressed 16 bit image of every frame, we can revisit the original master and rework it through the process using 10 bit target files instead of 8 bit for all displays, whether SDR or HDR and continue to improve the library. This is especially going to be noticed on SDR displays where banding shows up in the lower bit rates.

I’ve been bombarded with questions today asking me about remastering of movies shot digitally. There are several issues when delivering a movie shot in digital to the consumer whether using DVD, Blu-ray or OTT streaming. These issues become greatly amplified when you start moving into the Ultra HD realm, especially with the various color space issues and HDR formats. With the consumer TV market HDR and UHD are not standard. Color space can be DCI-P3 or REC2020. HDR standards include HDR-10, DolbyVision, HLG and variations that TV manufacturers are implementing. Even within a single manufacturer you have sets that can generate different levels of brightness in HDR. You can have sets that max out at 500nits and others at 1,000 nits. When viewing video on the different levels of color and brightness you end up having a different threshold for the Flicker Fusion where the movement causes a visual flicker. On lower end panels this is much more noticable than higher end panels. It becomes really obvious when videos shot digitally at 50/60 fps is played back on sets that don’t support the higher frame rate and have to stepped down to 25/30 fps.

When preparing videos and movies to be streamed OTT you can improve the user experience substantially by creating different masters for various platforms from mobile phones to the highest end HDR Ultra HD television.

I had a conversation today with someone who was asking me about film remastering. His first question was “if a movie was shot in digital format, then you don’t have to do anything but encode it right?” While several movies are being shot in digital format, there is a long held belief by many in the industry that film provides a much better look and feel for movies. We first learned this when working on the Interstellar project where we had to review our compressed digital delivery along side the original film output. Directors all take great care in their art, and rightfully so, as it’s their expression to the world of story they want to show and tell. Some directors will even go as far as choosing the type of film that they shoot on to get a particular look. This attention to detail is something that we spent a lot of time on when working on The Good The Bad and The Ugly project as we not only were trying to recreate the directors vision of the film, but also to match the choices made in lighting and apply coloring techniques to recreate the style of the print.

There are several considerations that have to be made when delivering a movie to the consumer on a TV over the internet. First and foremost, we have to look at what can be done to optimize the number of bits that are being streamed while trying to retain the original vision of the movie. A typical stream is going to deliver 6 to 8 gigabytes of data, which has been compressed down from the original 4 to 7 terabytes of raw digital footage. There is a significant amount of data to remove in order to make that work.

There are many areas of remastering techniques that are used on both analog and digital masters. One area that we are currently doing a lot of experimentation with and seeing some great results is film grain. Film grain provides a unique look to a film and helps the video being shown to get away from that plastic look that is especially prevalent in modern video that is shot on high end digital sensors at 60 fps. While that look is really great for showing off the color and brightness of the latest generation 4K HDR television sets, it can be off-putting for a movie experience. This is where grain can be your friend. By having grain, film has a more natural and fluid look. Capturing that grain is your enemy however, when trying to create a compressed digital file to be streamed. Grain is realized in pixels as what appears to be random patterns of different variations in the lighting of textures within a scene. This typically wreaks havoc when you are trying to compress a scene as compression does really well when you have long stretches of the same colored pixels in a row and does far worse when there are lots of subtle variations. There are a lot of grain filters that can be used during the post production process that can take the digital images and make them appear move film like. Where we are doing a bunch of work is to add that filter post expansion on the client side within the player as opposed to upstream pre-compression. This allows us to gain a better compression ratio but still apply the same “look and feel” of the graining filter that was desired.

With new techniques and tools literally coming out every week, and new projects coming on board we have the fun job of both redoing movies we have previously remastered and compressed and applying the new methods to improve them as well as taking some of the latest and greatest state of the art digital movies and applying new methods to them to show even greater improvement. This job is sort of like the guys that paint the Golden Gate Bridge, it’s never done. By the time they get to one end, it’s time to go back and restart.

So wanting to stay in touch with the DirecTV 4K offering I contacted them in late January to have my DirecTV serivce upgraded to 4K. They finally came yesterday. I stayed home from work while the technician performed my upgrade.

The first interesting issue was that I was told I had to have my “genie” unit replaced. That is my main DVR / Receiver which seems normal as it was installed 4 years ago. The new unit was required to support 4K, however, the unit itself does not output 4K. In order to display 4K on my main TV, he had to install (and I had to lease or purchase) a second TV controller, a “remote genie” For this he had to install a signal splitter in my A/V closet and have both the genie and remote genie connected.

After installing the devices and completing the setup we had to wait for the unit download an update to install the 4K support. We waited for an hour and the unit hadn’t updated and it stated that the TV doesn’t support 4K. My technician, who by the way was really great and courteous, said that they had reports of this delay issue in upgrading the software. After a few hours we gave up and he gave me his number and I told him I’d ping him when the update downloaded.

Even though I was confident that my wiring was good, he was concerned that since we were connected to port 1 of the Sony TV it might not support 4K input. To demonstrate the wiring was okay, I hooked up my NP-1 on port 1 and my Roku Ultra on port 2, and both were outputting 4K to the TV.

He’s meant to come back today and has been able to force the firmware update to allow it to support 4K. I’ll post an update once the next chapter takes place.